Silicone oil capacity control using polyurethane belt

ABSTRACT

Lubricant is conveyed from a supply reservoir to an opening in a dispensing reservoir by an annular absorbant member, and at a rate which will maintain a desired predetermined volume of lubricant within the latter. The dispensing reservoir has a roller partially immersed in the lubricant for dispensing the latter. An overflow permits lubricant conveyed in excess of the desired predetermined volume to flow back into the supply reservoir.

United States Patent Braun et al.

[451 Mar. 26, 1974 SILICONE OIL CAPACITY CONTROL USING POLYURETHANE BELT Inventors: Oskar .1. Braun, Williamson; Frank V. Onorati, Rochester, both of NY.

Assignee: Xerox Corporation, Stamford,

Conn.

Filed: Dec. 5, 1972 Appl. No.: 312,399

US. Cl. 222/109, 222/187, 222/414, 198/129, 118/637 Int. Cl G03g 13/10 Field of Search 222/109, 414, 187; 184/64, 184/103 R; 432/59; 219/216; 118/260, 262, 637; 198/129 References Cited UNITED STATES PATENTS 6/1969 Adamek 219/216 3,557,752 l/1971 Hakanson 118/637 3,368,526 2/1968 Matsumoto.... 118/637 1,703,963 3/1929 Scruby 198/129 Primary Examiner stanley 1-1. Tollberg Assistant Examiner-Larry Martin Attorney, Agent, or Firm-Earl T. Reichert [57] ABSTRACT Lubricant is conveyed from a supply reservoir to an opening in a dispensing reservoir by an annular absorbant member, and at a rate which will maintain a desired predetermined volume of lubricant within the latter. The dispensing reservoir has a roller partially immersed in the lubricant for dispensing the latter. An overflow permits lubricant conveyed in excess of the desired predetermined volume to flow back into the supply reservoir.

2 Claims, 2 Drawing Figures SILICONE OIL CAPACITY CONTROL USING POLYURETHANE BELT BACKGROUND OF THE INVENTION This invention relates to an improvement in an electrostatic copying machine (copier), but more particularly, to an improvement in a lubricator for a fuser assembly of such a machine.

In the practice of xerography as described in U. S. Pat. No. 2,297,691 to Chester F. Carlson, a xerographic surface comprising a layer of photoconductive insulating material affixed to a conductive backing is used to support electrostatic images. In the usual method of carrying out the process, the xerographic plate is electrostatically charged uniformly over its surface and then exposed to a light pattern of the image being reproduced to thereby discharge the charge in the areas where light strikes the layer. The undischarged areas of the layer thus form an electrostatic charge pattern or latent image in conformity with the configuration of the original pattern.

The latent electrostatic image may then be developed by contacting it with a finely divided electrostatically attractable material, such as a resinous powder. The powder is held in the image areas by the electrostatic fields on the layer. Where the field is greatest, the greatest amount of material is deposited; and where the field is least, little or no material is deposited. Thus, a powder image is produced in conformity with the image of the copy being reproduced. The powder is subsequently transferred to a sheet of paper or other transfer member and suitably affixed to thereby form a permanent print.

The latest concept for copiers utilizes high speed flash exposure of a document, and a moving photoconductive material in the form of an endless belt which is continuously charged. Additionally, such copiers are provided with a developing system which supplies toner particles in relatively large quantities for solid area coverage, such as a magnetic brush developing apparatus. Thus, after the belt passes the magnetic brush assembly for example, a xerographic powder image is formed on the belt which corresponds to the electrostatic latent image. This powder image is then transferred to a support surface (e.g., a sheet of paper) to which it is fused I by a fusing assembly whereby the powder image is caused to adhere to the support surface permanently.

One method which is commonly used to fuse the powder image to the support surface, involves conveying the latter between two fusing rollers, one of which is heated. To prevent the powder image carried by the support surface from sticking to the fuser roller contacting the powder image, the latter roller is often lubricated with a film of silicone oil. This is accomplished by dispensing the silicone oil from a reservoir by means of a dispensing roller which is mounted within the reservoir for rotation about a horizontal axis and which is partially immersed in the silicone oil. The rotating dispensing roller may contact the fusing roller directly, or an intermediate wick may be used. As an example of the latter arrangement, see US. Pat. No. 3,331,592.

With either of the above lubricating arrangements, however, the dispensing rate from the silicone oil reservoir varies because the amount of oil adhering to the rotating dispensing roller varies as the silicone oil supply is depleted; the reason for this is that the area of the dispensing roller in contact with the silicone oil supply decreases as the silicone oil supply decreases. Consequently, what is needed is a lubricator for dispensing lubricant to a fuser assembly at a substantially constant rate, and one which will operate for a substantially longer period of time than previously possible before the silicone oil supply must be replenished; such a lubricator should also be of a relatively simply construction having a minimum number of parts.

SUMMARY OF THE INVENTION The present invention is directed to a lubricator which dispenses lubricant at a substantially constant rate, does so with a minimum of parts, and which will operate for a substantially longer period of time than was previously possible before it is necessary to replenish the lubricant supply.

A dispensing reservoir adapted to contain a predetermined volume of lubricant has a dispensing roller mounted therein for rotation about a horizontal axis, the dispensing roller being partially immersed in the lubricant. The dispensing reservoir has overflow means for allowing lubricant in excess of the predetermined volume to flow into a supply reservoir containing the main supply of lubricant.

To assure that the predetermined volume of lubricant is maintained within the dispensing reservoir, an annular conveying member is rotated through the main lubricant supply and over an opening in the dispensing reservoir through which the conveyed lubricant is released. The lubricant is conveyed from the supply reservoir to the dispensing reservoir at a rate which will maintain the desired predetermined volume of lubricant within the dispensing reservoir.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view of an electrostatic copying machine embodying the principles of the invention.

FIG. 2 is a perspective view of the preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION For a general understanding of a copying machine in which the invention may be incorporated, reference is made to FIG. 1 in which the various system components for the machine are schematically illustrated. As in all electrostatic systems of the type illustrated, a light image of a document to be reproduced is projected onto the sensitized surface of a xerographic plate to form an electrostatic latent image thereon. Thereafter, the latent image is developed with an oppositely charged developing material to form a xerographic powder image, corresponding to the latent image on the plate surface. The powder image is then electrostatically transferred to a support surface to which it may be fused by a fusing device whereby the powder image is caused permanently to adhere to the support surface.

In the illustrated machine, an original D to be copied is placed upon the transparent support platen P fixedly arranged in an illumination assembly generally indicated by the reference numeral 10, arranged at the left end of the machine. While upon the platen, an illumination system flashes light rays upon the original thereby producing image rays corresponding to the informational areas on the original. The image rays are projected by means of an optical system for exposing the photosensitive surface of a xerographic plate in the form of a flexible photoconductive belt 112. The surface of the belt was made photosensitive by the previous step of uniformly charging the same by means of a corona generating device or corotron 13. In order to effect image processing, the belt 12 is arranged on a belt assembly generally indicated by the reference numeral 14.

The photoconductive belt assembly 14 is slidably mounted upon two support shafts. one of which is secured to the frame of the machine, and is adapted to drive a belt 12 in the direction of the arrow at a con stant rate. During this movement of the belt, the refleeted light image of an original on the platen is flashed upon the photoreceptor surface of the belt to produce electrostatic latent images thereon at an exposure station A.

As the belt surface continues its movement, the electrostatic image passes through a developing station Bin which there is positioned a developer assembly generally indicated by the reference numeral 15, and which provides development of the electrostatic image by means of multiple brushes 16 as the same moves through the development zone.

The developed electrostatic image is transported by the belt to a transfer station C where a sheet of copy paper is moved between a transfer roller and the belt at a speed in synchronism with the moving belt in order to accomplish transfer of the developed image solely by an electrical bias on the transfer roller. There is provided at this station a sheet transport mechanism generally indicated at 17 adapted to transport sheets of paper from a paper handling mechanism generally indicated by the reference numeraly 18 to the developed image on the belt at the station C.

After the sheet is stripped from the belt 12, it is conveyed into a fuser assembly generally indicated by the reference numeral 19 wherein the developed and transferred xerographic powder image on the sheet material is permanentlyaffixed thereto. To lubricate the fuser assembly (i.e., to apply a film of lubricant to one of the fuser rollers), a lubricator 20 is provided. After fusing, the finished copy is discharged from the apparatus at a suitable point for collection externally of the apparatus.

Referring to FIG. 2, the preferred embodiment of the invention will be discussed in detail. The lubricator 20 includes a supply reservoir 22 which contains a main supply 24 of the lubricant which is to be applied to the fuser assembly 19. As stated above, one of the problems with the lubricators of the prior art is the inability of these lubricators to dispense lubricant t the fuser assembly at a constant or substantially constant rate. To overcome this problem, lubricator includes a dispensing reservoir 26 which is adapted to contain a predetermined volume 28 of lubricant; this predetermined volume of lubricant is maintained by means described below. A dispensing roller 30 is mounted on a shaft for rotation about a horizontal axis, and is partially immersed in the predetermined volume 28 of lubricant. As the dispensing roller 30 rotates, a film of lubricant adheres thereto and is conveyed to a wick 32, (such as a felt pad) the latter being biased against the dispensing roller by the weight of a curved plate 34. Plate 34 is mounted to a cover 36 by means of a hinge 38 so that the plate can be lifted when it is desired to remove the wick 32.

The wick 32 transmits the lubricant from the dispensing roller 36 and applies it to a heated fuser roller 40 of fuser assembly 19; this fuser roller is the one which contacts the powder image on the sheet of paper. To assure that the wick 32 maintains contact with the fuser roller 40, a wick support plate 42 biases the wick against the fuser roller. When it is desired to remove the wick 32, the support plate 42 is released and moved in the direction of the arrow. Although not shown, a suitable material may be sewn to the wick 32 between the latter and the fuser roller 40 so as to reduce the friction between the wick and the rotating fuser roller.

To convey lubricant from the supply reservoir 22 to the dispensing reservoir 26, an annular conveying member 44 is mounted within the supply reservoir. The conveying member 44 is comprised of a belt 46 which is affixed by a suitable adhesive to an annular ring 48 having teeth 50 formed therein. The belt 46 may be polyurethane or other suitable absorbant material. To rotate the conveying member 44, a gear 52 having teeth 54 which mesh with the teeth 50 of ring 48 is mounted on the same drive shaft that the dispensing roller 30 is mounted on. Thus, the dispensing rollers 30 and the conveying member 44 are driven together. As the conveying member 44 rotates, the belt 46 rotates through the main supply 24 and absorbs lubricant therefrom. The lubricant is then conveyed by conveyor member 44 to a point over opening 56 in dispensing reservoir 26, where the lubricant is released by squeezing the belt 46 between gear 52 and a squeeze roller 58, the latter being rotatably supported; the released lubricant passes through the opening 56 into the dispensing reservoir 26. Lubricant conveyed to the dispensing reservoir in excess of the desired predetermined volume 28 flows over the overflow means 60 back to the supply reservoir 22. Lubricator 20 is designed so that lubricant is conveyed to the dispensing reservoir at a rate which will maintain the desired predetermined volume 28 within dispensing reservoir 26.

Other suitable means such as conventional pumps could also be used to convey lubricant from the supply reservoir 22 to the dispensing reservoir 26. To minimize the number of parts, however, it is preferable to use an annular conveying member as disclosed herein. Other annular conveying members could also be used; some might utilize buckets to pick up lubricant from the main supply such as the paddle wheel types of conveying members, while others might depend upon lubricant adhering to the conveying member, the adher ing lubricant then being wiped by a suitable mechanism from the conveying member over the opening 56.

What is claimed is:

l. The combination of a fuser roller with an improved lubricator for applying lubricant to the roller, the improved lubricator comprising:

a. a first reservoir adapted to contain a supply of lubricant;

b. a second reservoir adapted to contain a predetermined volume of the lubricant, the second reservoir having an opening in the top thereof for receiving lubricant conveyed from the first reservoir and an overflow means located above the level of the supply of lubricant for allowing lubricant in excess of the predetermined volume of lubricant to flow into the first reservoir;

c. a dispensing roller for dispensing lubricant from the second reservoir, the dispensing roller being mounted within the second reservoir for rotation about a substantially horizontal axis, the dispensing roller being partially immersed in the predetermined volume of lubricant;

. a wick in contact with both the fuser roller and the dispensing roller, and means movably mounted for biasing the wick into contact with both of said rollers',

. an annular conveyor member mounted so that the predetermined volume of lubricant with the second reservoir, the annular conveyor member including an annular ring and an absorbent annular belt affixed to the outer annular periphery of the latter, the inner annular surface of the ring having teeth formed therein, a drive gear rotatably mounted and meshing with the teeth in the annular ring, and a squeeze roller mounted above the opening in the second reservoir and in squeezing contact with the annular belt, whereby lubricant rotatably conveyed from the first reservoir and over the opening in the second reservoir is squeezed from the annular conveyor member and flows into the opening.

2. The combination set forth in claim 1, wherein the fuser roller and the wick are disposed above one of the reservoirs. 

1. The combination of a fuser roller with an improved lubricator for applying lubricant to the roller, the improved lubricator comprising: a. a first reservoir adapted to contain a supply of lubricant; b. a second reservoir adapted to contain a predetermined volume of the lubricant, the second reservoir having an opening in the top thereof for receiving lubricant conveyed from the first reservoir and an overflow means located above the level of the supply of lubricant for allowing lubricant in excess of the predetermined volume of lubricant to flow into the first reservoir; c. a dispensing roller for dispensing lubricant from the second reservoir, the dispensing roller being mounted within the second reservoir for rotation about a substantially horizontal axis, the dispensing roller being partially immersed in the predetermined volume of lubricant; d. a wick in contact with both the fuser roller and the dispensing roller, and means movably mounted for biasing the wick into contact with both of said rollers; e. an annular conveyor member mounted so that the bottom thereof is immersed in the supply of lubricant within the first reservoir and the top thereof is disposed over the opening in the top of the second reservoir, the annular conveyor being adapted to convey lubricant from the first reservoir to the second reservoir at a rate which will maintain the predetermined volume of lubricant with the second reservoir, the annular conveyor member including an annular ring and an absorbent annular belt affixed to the outer annular periphery of the latter, the inner annular surface of the ring having teeth formed therein, a drive gear rotatably mounted and meshing with the teeth in the annular ring, and a squeeze roller mounted above the opening in the second reservoir and in squeezing contact with the annular belt, whereby lubricant rotatably conveyed from the first reservoir and over the opening in the second reservoir is squeezed from the annular conveyor member and flows into the opening.
 2. The combination set forth in claim 1, wherein the fuser roller and the wick are disposed above one of the reservoirs. 